Roll coupling trailer hitch assembly

ABSTRACT

A roll coupling assembly includes a roll torque transfer structure and an alignment mechanism. The torque transfer structure includes a first load bearing structure mountable to the rear of the tow vehicle, and a second load bearing structure mountable to the front of the trailer drawbar. Corresponding first and second load bearing surfaces cooperate so as to releasably mate with one another for towing of the trailer behind the tow vehicle. The bearing surfaces are distributed across a substantially planar interface between the rear of the tow vehicle and the front of the trailer drawbar so as to distribute to the tow vehicle torque imparted to the drawbar by relative rolling motion between the trailer and tow vehicle. The coupling alignment mechanism adjusts the relative orientation of the first and second load bearing surfaces so as to align them for mating to one another.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from United States Provisional PatentApplication Numbers:

61/080,737 filed Jul. 15, 2008, entitled, Roll-Coupled Transfer Trailer;61/104,365 filed Oct. 10, 2008, entitled, Roll Coupling Hitch Assembly;61/105,864 filed Oct. 16, 2008, entitled, Self Aligning Roll CouplingHitch Assembly; and61/159,926 filed Mar. 13, 2009, entitled, Self-Aligning Roll-CouplingHitch Assembly.

For the United States only, this application is a Continuation-in-Partof the U.S. application Ser. No. 12/216,981, filed Jul. 14, 2008,entitled Roll Coupling Trailer Hitch Assembly.

FIELD OF THE INVENTION

The present invention relates to improvements in devices for connectinga trailer to the rear of a tow vehicle so as to roll couple the trailerto the tow vehicle to improve vehicle stability.

BACKGROUND OF THE INVENTION

In the prior art applicant is aware of U.S. Pat. No. 1,524,503, whichissued Jan. 27, 1925 to Bennett et al for Trailer Coupling, U.S. Pat.No. 1,552,620, which issued Sep. 8, 1925 to Knox for Trailer Coupling,U.S. Pat. No. 2,460,466, which issued Feb. 1, 1949 to Nogle for TrailerDolly, U.S. Pat. No. 2,360,902, which issued Oct. 24, 1944 to Simmonsfor Vehicle, U.S. Pat. No. 1,957,917, which issued May 8, 1934 to Storeyfor Tractor, U.S. Pat. No. 3,298,706, which issued Jan. 17, 1967 toLyall for Heavy Motor Vehicles and Equipment, U.S. Pat. No. 1,643,885,which issued Sep. 27, 1927 to Gill for Means for Loading and HaulingAutomobiles.

Knox and Bennett describe trailer coupling assemblies using twovertically aligned hitch points for the purpose of automaticallyelevating a trailer while connecting the trailer to the tow vehicle inorder to transfer trailer weight to the rear axle of the tow vehicle.

Nogle discloses a wheeled dolly having two horizontally alignedconnecting points to carry the weight of the front of a trailer towedbehind the dolly.

Simmons describes providing one or more connection points for thepurposes of selectively transferring weight from one portion of thevehicle to another and to change the angular alignment of theinterconnected vehicles.

Storey discloses providing articulation to interconnect two parts of avehicle. Applicant is aware that in the prior art it is known to providebooster axles designed to be attached to the front or rear of vehiclesfor the purpose of transferring weight from the vehicles to the boosteraxles to increase the carrying capacity of the vehicles.

By way of example, Lyall describes an articulating booster axle designedto transfer part of a crane's weight to a booster axle that trails ortracks behind the crane.

Gill teaches an automobile carrier with a hitch assembly located aft ofthe truck frame.

Applicant has in the present invention improved on his inventiondescribed and claimed in his United States patent application entitledRoll coupling Trailer Hitch Assembly, filed Jul. 14, 2008, and publishedJan. 15, 2009, under publication number US2009-0014982.

As commercial vehicles increase load capacity by increasing the numberof weight bearing axles over a given length, the vehicle's centre ofgravity is raised and the vehicle becomes increasingly unstable while inmotion. In applicant's experience, the governing governmentalauthorities have started to restrict weights on combination vehicleswhere the trailers are attached to the rear of tow vehicles (includingdump truck and pony trailer combinations, or other truck and trailercombinations, or combinations where a trailer is towed by anothertrailer) in order to reduce the number of accidents involving thesevehicles.

In applicant's experience, at least with respect to truck and trailercombinations, roll coupling these types of vehicle combinations mayimprove safety and provide an alternative to reducing weight limits bythe governing authorities. To the knowledge of applicant, tridem (thatis, three axle) pony trailers are presently limited to 21,000 kgs on thetrailer axles in British Columbia, Canada. The previous maximum weightfor a tridem axle group in British Columbia was 24,000 kgs.

Roll coupling may provide improved yaw and roll stability where there isroll coupling between the tow vehicle and towed trailer when used inconjunction with sufficiently torsionally strong draw bars andcorresponding supporting framework on the trailer to resist twistingduring initial rolling motion of the trailer and so as to import theresulting torque to the roll coupling and thence to the tow vehicle. Asingle roll coupling hitch or a plurality of diagonal, horizontal orvertically aligned hitch assemblies and contact points may be used asrequired for different applications to provide roll coupling and so asto allow legal hitch offset distances, and so as to provide redundantcritical hitch components and so as to reduce operating stresses onindividual hitch components. Using common hitch components wheneverpossible also enables the tow vehicle to be used with trailers equippedwith lunette rings, that is, which are not equipped with roll couplers.

A dynamic analysis was conducted to simulate the performance of rollcoupling utilizing the University of Michigan Transportation Institute(UMTRI) yaw/roll model for a tandem truck/tridem pony trailer for thefollowing four conditions: Loaded truck (GVW 26 100 kg), loaded trailer(GVW 21 000 kg)—no roll-coupling; Empty truck (GVW 13 695 kg), loadedtrailer (GVW 21 000 kg)—no roll-coupling; Loaded truck (GVW 26 100 kg),loaded trailer (GVW 24 000 kg)—roll-coupling; and, Empty truck (GVW 13695 kg), loaded trailer (GVW 24 000 kg)—roll-coupling.

The truck trailer dimensions are summarized in Table 1. Loads wereplaced on the truck and trailer so that the maximum axle group loadswere achieved at maximum legal height (4.15 m).

TABLE 1 Summary of truck/trailer dimensions Parameter Dimension (m)Truck Wheelbase 6.109 Drive group spread 1.397 Hitch offset 1.448 Hitchheight 0.591 Trailer Wheelbase 6.464 Trailer group spread 2.769 Deckheight 0.864

The following performance measures were evaluated for each loadcondition. The performance measures are described below. Handlingperformance—oversteer transition (H-P1); Handling performance—understeercoefficient at 0.3 g (H-P2); Handling performance—understeer coefficientat 0.15 g (H-P3); Handling performance—understeer coefficient at 0.25 g(H-RTAC); Static rollover threshold (SRT); Load transfer ratio (LTR);Rearward Amplification (RA); Lateral friction utilization (LFU);Friction demand (FD); Low-speed off-tracking (LSOT); High-speedoff-tracking (HSOT); Transient off-tracking (TOT).

The simulation results are summarized in Table 2.

The handling performance of the loaded truck/pony trailer was improvedwith roll coupling. The degree of oversteer occurring at high lateralaccelerations was reduced and the transition from understeer tooversteer occurred at a higher lateral acceleration when roll couplingwas present. The handling performance was essentially the same for boththe non roll coupled and roll coupled trailers in combination with anempty truck. However the roll coupled trailer exhibited less understeerand therefore has slightly improved handling characteristics.

TABLE 2 Simulation Results Tandem truck/Tridem pony trailer Non-rollNon-roll Roll Roll coupled coupled coupled coupled Performance LoadedEmpty Loaded Empty Performance Measures Standard Truck Truck Truck TruckHandling performance >0.20 g's 0.209 0.373 0.217 0.318 (point #1)Oversteer transition Handling performance >−4.45 deg/g −4.081  0.671−3.175  0.339 (point #2) USC at 0.3 g Handling performance >0.50, 0.9612.627 1.515 2.049 (point #3) <2.00 deg/g USC at 0.15 g Handlingperformance >−4.45 deg/g −2.171  2.530 −1.159  1.439 (RTAC) USC at 0.25g Static rollover threshold >0.35 g's 0.348 0.410 0.372 0.513 Loadtransfer ratio <0.60 0.725 0.709 0.524 0.510 Rearward amplification<2.00 1.992 2.011 1.728 1.841 Low-speed lateral <0.80 0.457 0.362 0.5320.396 Friction utilization (low friction) Friction demand <0.10 0.1850.441 0.191 0.424 Low-speed offtracking <5.60 m 2.483 2.341 2.591 2.468High-speed offtracking <0.46 m 0.559 0.330 0.495 0.374 Transientofftracking <0.80 m 0.571 0.518 0.492 0.423 Load Height - truck (m)4.15  2    4.15  2    Load Height - trailer (m) 4.15  4.15  4.15  4.15 Steering axle load (kg) 9 100     5 665     9 100     5 665     DriveGroup load (kg) 17 000     8 030     17 000     8 030     Trailer load(kg) 21 000     21 000     24 000     24 000     Gross CombinationWeight (kg) 47 100     34 695     50 100     37 695    

Stability was improved under both loading conditions with roll coupling,enabling the static rollover performance standard of 0.35 g to beachieved when coupled with a loaded truck.

Roll coupling resulted in an improvement dynamic performance for alldynamic performance measures (that is, LTR, RA, and TOT as definedbelow). The use of roll coupling allowed all the dynamic performancestandards to be achieved under both loading conditions. Of particularnote is the significant improvement in load transfer ratio in the orderof 28% under both loading conditions.

The low-speed performance was largely unaffected by roll coupling.However this configuration exhibited high levels of friction demand (FD)with and without roll coupling, particularly when the truck wasunloaded. This implies that only a loaded truck should be used to haul aloaded trailer under low traction conditions. Even with a loaded truckcare should be taken when negotiating tight turns.

The high-speed offtracking performance standard (<0.46 m) was achievedfor both coupling methods when hauled by an empty truck. The standardwas not achieved for either coupling method when hauled by a loadedtruck, but performance was marginally better with a roll coupledtrailer.

Understeer Coefficients (USC) were used to evaluate handling performanceat steady-state conditions by calculating the understeer coefficient at0.15 g, 0.30 g, (TAC 0.25 g). This measure is expressed in degrees per gwhich represents the slope of the handling diagram. Positive andnegative values indicate understeer and oversteer levels respectively.This performance measure is determined during a ramp steer manoeuvre(ramp steer rate of 2 deg/sec at steering wheel) at a forward velocityof 100 km/h. The pass/fail criterion is addressed by comparing theundersteer coefficient with the critical understeer coefficient, whichcan be expressed as −Lg/U2, where U is the vehicle speed (U=27.77 m/s(100 km/h)), L is the tractor or truck wheelbase (in metres), and g isacceleration due to gravity (9.81 m/s²). If the value of the understeercoefficient is greater than the critical value, the vehicle will meetthe criterion (TAC performance standard). In addition the lateralacceleration where the transition from understeer to oversteer (that is,the point where the understeer coefficient is zero) is also computed.

Static Rollover Threshold (SRT) is the level of steady lateralacceleration beyond which the configuration rolls over. The measure isexpressed as the lateral acceleration (in g's) at which all wheels onone side, except the steer axle, lift off the ground. Configurationperformance is considered satisfactory if the static rollover thresholdis greater than or equal to 0.35 g.

Load Transfer Ratio (LTR) is defined as the ratio of the absolute valueof the difference between the sum of the right wheel loads and the sumof the left wheel loads, to the sum of all the wheel loads. The frontsteering axle is excluded from the calculations because of itsrelatively high roll compliance. Configuration performance is consideredsatisfactory if the LTR is less than or equal to 0.60 (TAC performancestandard). This performance measure is evaluated during a rapid lanechange manoeuvre conducted at 88 km/h, yielding a lateral accelerationamplitude of 0.15 g and a period of 2.5 seconds at the tractor'ssteering axle.

Rearward Amplification (RWA) is defined as the ratio of the peak lateralacceleration at the mass centre of the rearmost trailer to thatdeveloped at the mass centre of the tractor. Configuration performanceis considered satisfactory if the RWA is less than or equal to 2.0,which is the current TAC performance standard. This performance measurewas evaluated in the same manoeuvre as LTR.

Friction Demand (FD) performance measure describes the non-tractive tirefriction levels required at the drive axles of a tractor. Excessivefriction demand is a contributing factor to jack-knife and also resultsin excessive tire wear. Friction demand is the absolute value of theratio of the resultant sheer force acting at the drive tires divided bythe cosine of the tractor/trailer articulation angle to the verticalload on the drive tires. Configuration performance is consideredsatisfactory if FD is less than or equal to 0.1 (TAC performancestandard). This performance measure is evaluated in a 90-degree turn ata vehicle speed of 8.25 km/h. During the manoeuvre, the centre of thefront steer axle tracks an arc with a 12.8-m radius (approximately a14-m outside-wheel-path radius).

Lateral Friction Utilization (LFU) is a measure proposed by NRC tocharacterize the highest level of the lateral friction utilization atthe steering axle. LFU is defined as the ratio of the sum of lateralforces to the vertical load, and the peak tire/road coefficient ofadhesion. The tires of a steering axle that achieves a lateral frictionutilization level of 1 are said to be saturated. Configurationperformance is considered satisfactory if LFU is less than or equal to0.80 (NRC recommended performance standard). Initially this performancemeasure was evaluated on a high friction surface. This measure wasmodified by evaluating LFU on low friction surfaces, which are morecritical for steering performance, by using low friction tirecharacteristics (μ=0.2). This performance measure was evaluated usingthe same manoeuvre as FD.

Low Speed Offtracking (LSOT) was measured as the maximum lateraldisplacement of the centre-line of the last axle of the configurationfrom the path taken by the centre of the steer axle. Configurationperformance is considered satisfactory if LSOT is less than or equal to5.6 m (TAC performance standard). This performance measure was evaluatedusing the same manoeuvre as FD and LFU.

High Speed Steady State Offtracking (HSOT) was measured as the maximumlateral displacement of the centre-line of the last axle of theconfiguration from the path taken by the centre of the steer axle.Configuration performance is considered satisfactory if HSOT is lessthan or equal to 0.46 m (TAC performance standard). This valuerepresents a minimal clearance of 0.15 m between the trailer tires andthe outside of a 3.66-m wide conventional traffic lane. This performancemeasure was evaluated when the vehicle is operated in a 393-m curveradius, at a speed of 100 km/h, thereby attaining a steady lateralacceleration level of 0.2 g.

Transient Offtracking (TOT) was measured as the maximum lateraldisplacement of the centre-line of the last axle of the configurationfrom the path taken by the centre of the steer axle. Configurationperformance is considered satisfactory if TOT is less than or equal to0.8 m (TAC performance standard). This performance measure was evaluatedin the same manoeuvre as LTR and RWA.

SUMMARY OF THE INVENTION

A roll coupling system for roll coupling the drawbar of a trailer to therear of a tow vehicle may be characterized as including:

-   -   a) a roll torque transfer structure including at least one first        load bearing surface on a first load bearing structure mountable        to the rear of the tow vehicle and adapted to be mounted closely        adjacent thereto, and at least one second load bearing surface        on a second load bearing structure mountable to the front of the        trailer drawbar, wherein the first and second load bearing        surfaces cooperate so as to releasably mate with one another for        towing of the trailer behind the tow vehicle and, when the        trailer is so mated to the tow vehicle, are distributed across a        substantially planar interface, which may be vertical, between        the rear of the tow vehicle and the front of the trailer drawbar        so as to distribute torque imparted to the drawbar by relative        rolling motion between the trailer and tow vehicle to the rear        of the tow vehicle by distribution of resulting moments which        are transferred to the tow vehicle so that the cumulative        combined roll resistance of the tow vehicle and trailer resist        the rolling of the trailer about the drawbar, and    -   b) a coupling alignment mechanism to adjust the relative        orientation of the first and second load bearing surfaces in the        substantially planar interface so as to align the first and        second load bearing surfaces for the mating with one another.

The coupling alignment mechanism may include at least one self-aligningguide cooperating between the first and second load bearing structuresso as to urge relative alignment about a roll axis of the drawbar of thefirst and second load bearing surfaces as the rear of the tow vehicleand the front of the drawbar are urged together so as to urge the firstand second load bearing surfaces to the mate with one another, whereinthe coupling alignment mechanism includes a selectively rotatable rollcoupler, selectively rotatable about the roll axis of the trailerdrawbar, mounted between the front of the drawbar and the rear of thetow vehicle, and wherein the selectively rotatable coupler includes aselectively releasable lock, wherein the lock locks said coupler in afixed roll coupling position, fixed relative to rotation about said rollaxis, upon a pre-set forward translation speed being attained by the towvehicle and trailer.

The first and second load bearing surfaces may mate at, at least twospaced apart load transfer points on the substantially planar interface.The first and second load bearing structures may be mounted at each ofthe at least two spaced apart load transfer points. At least oneself-aligning guide may be mounted at least one of the two spaced apartload transfer points.

In one embodiment the planar interface is inclined from the vertical sothat an upper position of the planar interface is tipped towards the towvehicle so as to provide a pre-load roll force acting on the trailer tocause the trailer to lean into a corner, wherein an upper load transferpoint is positioned forward of a lower load transfer point of the spacedapart load transfer points.

Typically the first and second load bearing structures include male andfemale load bearing structures. Further, each self-aligning guide mayinclude at least one substantially v-shaped guide for guiding the maleload bearing structure into mating engagement in the female load bearingstructure. Each v-shaped guide may include a spaced apart pair ofsubstantially v-shaped guides, where the pair of substantially v-shapedguides may be substantially parallel and wherein each guide may includea pair of arms forming the v-shape, and where the arms may extendsubstantially orthogonally from the substantially planar interface.

In one embodiment, the male load bearing structure includes a hook andthe female load bearing structure includes a collar having an aperturesized for snug mating with the hook so as to journal the hook in theaperture. The hook may include a pintle hook and the collar may includea lunette ring.

The spaced apart load transfer points may form a substantially lineararray. The array may be vertical, horizontal or otherwise aligned in thesubstantially planar interface.

The lock for locking the roll coupler includes a male portioninterlocking into a corresponding female portion. In one embodiment themale portion is urged into interlocking with the female portion by adefault driver biasing the male portion into registry with the femaleportion so that the roll coupling defaults to the locking of the rollcoupler to roll couple the tow vehicle and trailer together. The defaultdriver alignment mechanism may include a resilient driver, for example aspring. The lock may further include a return biasing driver forselectively unlocking the roll rotatable coupler so as to dis-engage theroll coupling of the tow vehicle and trailer.

The roll coupling may include in one example which is not intended to belimiting, a pair of plates, a first plate of which is adapted to bemounted to the rearmost end of the tow vehicle, a second plate of whichis adapted to be mounted to the front end of the drawbar of the trailer.The pair of plates are substantially flush against one another when thetrailer is coupled to the tow vehicle. The pair of plates pivot relativeto one another in flush rotation one over the other. Each plate in thepair of plates has an aperture. When the apertures in the plates arealigned, the trailer is aligned for roll coupling with the tow vehicle.The male portion is mounted in one of the apertures. The other of theapertures is the female portion. The male portion is an elongate memberwhich is projected into snug mating with said female portion to effectsaid roll coupling. The default driver urges the male portion, such as apin member or the latch member, into the female portion to lock the rollcoupler.

In one embodiment the default driver is a linear driver biasing themember linearly into registry in the aperture of the female portion. Thereturn driver is, selectively rotatable about the roll axis of thetrailer drawbar, and mounted between the front of the drawbar and therear of the tow vehicle. Further, the selectively rotatable coupler mayinclude a selectively releasable lock. The lock locks the coupler in afixed roll coupling position, fixed relative to rotation about the rollaxis. The coupler and the lock may be mounted on the front end of thedrawbar.

The alignment mechanism may also include at least one roller mounted onthe pins so as to mate with the V-shaped guides on the load bearingstructures.

The roll coupling lock may be adapted to be biased into locking of theroll coupling upon receipt of a locking trigger corresponding to thepre-set forward translation speed of the truck and trailer. A defaultlocking driver may be provided to lock the lock and, again, a returndriver may be provided for unlocking the lock. The locking driver maycontinually bias the lock into the fixed roll coupling position. Thereturn driver return biases the locking driver into its unlockedposition so as to prevent the locking of the roll coupling until thelocking trigger is received, whereupon the return driver dis-engagesfrom the return biasing of the locking driver. Again, the locking driverand the return driver may both be resiliently biased drivers, that isthey may both be resilient drivers.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following figures, similar characters of reference denotecorresponding parts in each view.

FIG. 1 is, a partially cutaway plan view of a first embodiment of theroll coupling assembly according to the present invention.

FIG. 2 is, in perspective view, the roll coupling assembly of FIG. 1.

FIG. 2 a is, in partially cutaway perspective view, the roll couplingassembly of FIG. 2 in its open position.

FIG. 2 b is a view of FIG. 2 a with the roll coupling assembly in itsclosed position.

FIG. 3 is, in perspective view, the roll coupling assembly of FIG. 2mounted to a trailer drawbar.

FIG. 4 a is, in perspective view, the roll coupling assembly of FIG. 3with the roll coupling assembly mounted together and the drawbar pivotedupwardly.

FIG. 4 b is the view of FIG. 4 a with the drawbar lowered to thehorizontal.

FIG. 4 c is the view of FIG. 4 b with the drawbar lowered belowhorizontal.

FIG. 5 a is, in perspective view, the female load transfer structureaccording to a second embodiment of the roll coupling assembly accordingto the present invention mounted on the rear of a tow vehicle frame.

FIG. 5 b is, in perspective view, the male load transfer structure ofthe embodiment of FIG. 5 a mounted on the front end of a drawbar.

FIG. 6 is, in perspective view looking towards the rear of the towvehicle, the roll coupling assembly of FIGS. 5 a and 5 b.

FIG. 7 is the roll coupling assembly of FIG. 6 in perspective viewlooking at the front of the drawbar.

FIG. 8 is a further embodiment of the roll coupling assembly of FIG. 7wherein the male load transfer structure is selectively rotatable aboutthe roll axis of the drawbar.

FIG. 9 is, in perspective view, a further embodiment of the rollcoupling assembly according to the present invention.

FIG. 10 is, in perspective view, the roll coupling assembly of FIG. 9with the drawbar rotated in a horizontal plane.

FIG. 11 is, in perspective view, a further alternative embodiment of theroll coupling assembly of FIG. 9.

FIG. 12 is, in perspective view, the roll coupling assembly of FIG. 11with the drawbar rotated in a horizontal plane.

FIG. 13 is, in left side elevation view, a further embodiment of theroll coupling assembly according to the present invention.

FIG. 14 is, in left side elevation view, yet a further embodiment of theroll coupling assembly according to the present invention.

FIG. 15 is, in left side elevation view, the roll coupling assembly ofFIG. 13 adapted to provide selective roll rotation of the couplingassembly relative to the drawbar.

FIG. 16 is, in perspective view, a further embodiment of a roll couplingassembly according to the present invention.

FIG. 17 is a variant of the roll coupling assembly of FIG. 13illustrated in left side elevation view.

FIG. 18 is a further variant of the roll coupling assembly of FIG. 13illustrated in left side elevation view.

FIG. 19 is a cross sectional view along line 19-19 in FIG. 18.

FIG. 20 is, in perspective view, a further embodiment of a roll couplingassembly according to the present invention.

FIG. 21 is, in perspective view, the roll coupling assembly of FIG. 20with the drawbar rolled about the drawbar roll axis.

FIG. 22 is, in perspective view, the roll coupling assembly of FIG. 20,with the drawbar rotated in a horizontal plane.

FIG. 23 a is, in perspective view, a variant of the roll couplingassembly of FIG. 20.

FIG. 23 b is an enlarged partially cut-away perspective view of thecoupling assembly between the pintle hitches and drawbar of FIG. 23 a.

FIG. 24 is, in perspective view, the roll coupling assembly of FIG. 20mounted to a dolly.

FIG. 25 is an enlarged view of a portion of FIG. 24.

FIG. 26 is, in perspective view, the roll coupling assembly and dolly ofFIG. 24 with the drawbar and dolly rotated in a horizontal plane.

FIG. 27 is, in perspective view, a further embodiment of the rollcoupling assembly according to the present invention, with the drawbarrotated in a horizontal plane.

FIG. 28 is the roll coupling assembly of FIG. 27 with the drawbaraligned behind the tow vehicle.

FIG. 29 is the roll coupling assembly of FIG. 28 from a lowerperspective view.

FIG. 30 is, the roll coupling assembly of FIG. 28, in side elevationpartially cut-a-way view.

FIG. 31 is, in partially cut-a-way view, an upper perspective view of afurther embodiment of the roll coupling assembly of FIG. 30.

FIG. 32 is, in lower perspective view, a further embodiment of the rollcoupling assembly according to the present invention with the drawbarrotated in a horizontal plane.

FIG. 33 is, in exploded partially cut-a-way perspective view, the rollcoupling assembly of FIG. 32.

FIG. 34 is, in perspective view, the roll coupling assembly of FIG. 32with the drawbar aligned behind the tow vehicle.

FIG. 35 is, in partially exploded view, the roll coupling assembly ofFIG. 34.

FIG. 36 is, in perspective view, a further embodiment of the rollcoupling assembly according to the present invention.

FIG. 37 is, in perspective view, the locking assembly of the rollcoupling of FIG. 36, with a locking assembly in its locked position.

FIG. 38 is, in perspective view, the locking assembly of FIG. 37 in itsopen position.

FIG. 39 is, in perspective view, a further embodiment of the rollcoupling assembly according to the present invention, with the alignmentforks on the drawbar removed to show how the hitch may also be used topull a conventional drawbar with a single lunette ring.

FIG. 40 is, in lower perspective view, a further embodiment of the rollcoupling assembly according to the present invention.

FIG. 41 is, in perspective view, the roll coupling assembly of FIG. 40.

FIG. 42 is, in partially cut-a-way perspective view, the roll couplingassembly of FIG. 40 illustrating the default or locking driver andreturn driver for locking the roll coupler upon attaining a pre-setspeed.

FIG. 43 is, in perspective view, a further embodiment of the rollcoupling assembly according to the present invention, with the rollcoupling locking assembly removed.

FIG. 44 is, in perspective view, the roll coupling assembly of FIG. 43with the roll coupler mounted in place.

FIG. 45 is, in perspective view, the roll coupling locking assembly ofFIG. 44.

FIG. 46 is, in partially cut-a way perspective view, the roll couplinglocking assembly of FIG. 45.

FIG. 47 is, in perspective view, a further embodiment of the rollcoupling assembly according to the present invention.

FIG. 48 is, in side elevation view, the roll coupling assembly of FIG.47.

FIG. 49 is, in perspective view, the roll coupling assembly of FIG. 47,with the drawbar assembly unhitched from the rear of the tow vehicle.

FIG. 50 is, in perspective view, a telescopic drawbar transfer trailerdolly adapted for roll coupled mounting to the tow vehicle using theroll coupling according to the present invention.

FIG. 51 is and alternative embodiment of the transfer trailer dolly ofFIG. 50.

FIG. 52 is, in plan view, the transfer trailer dolly of FIG. 51 mountedto a trailer frame having a gravel trailer box mounted thereon.

FIG. 53 is, in side elevation view, the trailer of FIG. 52 roll coupledto a gravel truck.

FIG. 54 is, in plan view, the transfer trailer dolly of FIG. 51 with thetransfer trailer dolly of FIG. 51 with the drawbar retracted.

FIG. 55 is a sectional view along line 55-55 in FIG. 54.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIGS. 1 to 4 illustrate a roll coupling hitch assembly which includes acoupler that engages with a vertical pin to allow yaw and pitch rotationwhile providing roll coupling to resist rolling about a horizontallongitudinal axis of the trailer (not shown). FIG. 1 illustrates a topview of king pin 10 in the process of engaging with a primary jaw 12having spur gear teeth 12 a that engage with teeth 14 a on a secondaryjaw 14 to transmit motion as the king pin forces the primary jaw lever16 rearward until the king pin comes to rest at the rear of the guideslot 18 in the coupler housing 20. As the primary jaw rotates clockwisearound pin 22 under pressure from the king pin, as would be the casewhen a tow vehicle backs into the trailer drawbar 38, the handle 24rotates clockwise in direction A to cause the latch 26 below the handleas best seen in FIG. 2 to engage with a dog 28 formed in the top surfaceof housing 20. This inhibits the coupler from inadvertently disengaging.

FIGS. 2 a and 2 b illustrate the jaw assemblies when they are open asshown in FIG. 2 a and closed as shown in FIG. 2 b. FIG. 2 shows the jawassembly installed in the housing 20. The housing side plates are notshown in FIG. 2. Housing 20 includes upper and lower guide plates 30having v-shaped entryways 30 a (see FIG. 3) to self-align the couplerwith kingpin 10 as the kingpin engages in the entryways duringconnecting in direction B the tow vehicle to the trailer. Entryways 30 aprovide self-aligning guides which allow coupling of the trailer to thetow vehicle on uneven ground where, otherwise, the male and femalecoupling structures would not readily align without for examplejacking-up the trailer on the low side. It is understood that althoughnot shown illustrated on all embodiments herein, it is intended thatself-aligning guides be provided on all embodiments where for examplesubstantially v-shaped guides may be aligned and positioned to guidelunette rings or pins onto their corresponding pintle hooks or collarsrespectively.

Rolling relative movement is resisted between the tow vehicle andtrailer when the coupler is engaged with king pin 10. Kingpin 10 isfixed on its opposite ends to a bracket 32 that attaches in theillustrated embodiment to the tow vehicle although this is not intendedto be limiting as it is intended to be within the scope of the presentinvention in this and the other embodiments taught herein that if it istaught that the pin is on the trailer and the receiving coupler on thetow vehicle, that the opposite arrangement is also included, forexample, that the kingpin or pins be on the trailer drawbar and thereceiver on the frame of the tow vehicle.

The lower platform 34 of bracket 32 is larger than the top plate tosupport the weight of the trailer drawbar 38 and facilitate yaw rotationwhen the combination tow vehicle and trailer turns a corner.

FIG. 3 illustrates the housing 20 with the side plates attached. Theside plates anchor the pitch rotation pins 36 on both sides of thehousing. The trailer drawbar 38 is pivotally attached to the housing viapitch pins 36 so that, as seen in FIGS. 4 a, 4 b and 4 c drawbar 38 maypitch relative to the tow vehicle in a range of motion C around the axisof pitch pin 36. The jaws are engaged with, and rotate around, the kingpin 10 in bracket 32 to provide yaw rotation of the drawbar relative tothe tow vehicle.

FIGS. 5 to 8 illustrate a second embodiment of roll coupling assemblyaccording to the present invention. The coupler is attached to the towvehicle as better described below instead of to the trailer. Thisembodiment is particularly suitable for trucks that have an exposedframe section at the rear of the vehicle such as logging trucks. As withthe embodiment of FIGS. 1 to 4, and other embodiments taught herein,again advantageously the coupling assembly is closely adjacent the rearof the tow vehicle so as to reduce interference at the back of the towvehicle. For example, in the first embodiment, if the tow vehicle is adump truck then interference with a load being dumped from the truck boxis minimized, that is, the load doesn't directly pour on to the coupler.

The truck frame rails 40 are attached to a rear cross member 42 that isused to hold the hitch bracket 44 in place. The hitch bracket may beattached directly to the cross member or alternatively it may becushioned with rubber blocks 46 to absorb shock and permit limitedmovement to avoid stressing hitch components when operating in roughterrain. However it is attached, the bracket provides upper and lowerguide plates 30 again with v-shaped guides 30 a to self-align thecoupler with the king pin 10 when the tow vehicle is being connected tothe trailer and to resist relative rolling movement about longitudinalaxis D (FIG. 8) between the tow vehicle and trailer. Someone skilled inthe art would know of many different ways to lock the trailer kingpin(s) 10 within the neck 30 b of guide plates 30 without restrictingyaw movement. In this embodiment, two jaws 48 are provided in lockingdevice 50. Locking device 50 holds the jaws open or closed. When open,the jaws do not obstruct guides 30 a or neck 30 b. As seen in FIG. 5 b,the forward end of the trailer drawbar 38 has kingpin 10 mountedvertically thereon. Kingpin 10 runs vertically through a metal block 52that also houses the pitch pin 36 to provide pitch rotation of thedrawbar about the pitch pin axis.

FIGS. 6 and 7 further illustrate the hitch assembly of FIG. 5. The jawlocking mechanism is shown in both views. The lock handle 50 rotates indirection G within a pin boss 51 attached to the distal end of a leafspring 54 so as to unhook arm 50 a from behind bracket 30 c. Spring 54is attached at its opposite end to the upper jaw 48 by means of bracket54 a. Moving and locking the handle 50 in either direction E deflectsthe spring in direction F applying spring pressure on to upper jaws 48to either open or close. Both jaws are rigidly connected via pin 56 sooperation of upper jaw 48 simultaneously operates lower jaw 48. Theupper jaw 48 is held open by engaging arm 50 b within latch 30 d bypulling back on, and rotation of handle 50.

FIG. 8 illustrates the trailer drawbar attached to the tow vehicleframe. The drawbar in this embodiment however provides a means ofselectively disabling the roll coupling to allow for roll rotation aboutroll axis (longitudinal axis) D. The drawbar is allowed to roll aboutroll axis pin 58 when the locking mechanism 60, latching located on bothsides of the drawbar, is disengaged by rotating the control handle 62rearwardly. This is useful for an operator where the tow vehicle andtrailer are knowingly going to be driven, usually slowly, over roughterrain where if the roll coupler were not de-coupled damage might occurto the coupler, frame of the trailer, and/or frame of the tow vehicle.

The third roll coupling assembly of FIGS. 9 to 12 illustrates how asingle hitch assembly may be utilized with safety chains or the like toachieve roll coupling.

FIG. 9 again illustrates the end of a tow vehicle (truck or trailer)frame 40 and a cross member 42. In this embodiment a pintle hookcoupling 64 is mountable to the cross member 42. The cross member 42also has two slotted arms 66 extending therefrom. The trailer drawbar 38assembly is connected with the tow vehicle by engaging a lunette ring 68mounted on the drawbar with the pintle coupler 64. A pair of oppositelydisposed ears 72 a are mounted to the drawbar under the lunette ring.The drawbar ears 72 a are attached to the slotted arms 66 using chains70 and hooks 74. The ears 72 a are mounted to the lower part of thedrawbar directly below the center of the lunette ring by a swivelbracket 72. Swivel bracket 72 rotates in direction H about pin 72 b whenthe tow vehicle turns a corner. The lower ends of the chains are mountedto the ears. The upper ends of the chains are attached to hooks 74.Hooks 74 engage in slots 66 a in slotted arms 66 as the drawbar lunettering is being lowered over the hook 64 a of the pintle coupler 64 whilethe trailer is being connected to the tow vehicle.

FIG. 10 illustrates the components of FIG. 9 as they would appear whenthe tow vehicle and trailer are making a turn. The chain swivel bracket72 has rotated in direction H within a slot on the lower forward end ofdrawbar 38. The rotation of bracket 72 avoids stressing chains 70 andhooks 74.

The chains 70 illustrated in FIGS. 9 and 10 are of sufficiently shortlength so as to be tight to thereby resist roll movement about axis Dbetween the tow vehicle and trailer. These chains can alternatively beattached directly to the drawbar on trailers operating in jurisdictionswhere more roll movement is permitted by law.

FIG. 11 illustrates an alternative arrangement substituting link rods 76for chains 70. Link rods 76 are pinned to arms 66 and swivel bracket 72using adjustable yokes 78. FIG. 12 illustrates the alternativearrangement of FIG. 11 as it would appear when the tow vehicle is makinga turn. Again swivel bracket 72 has rotated relative to the lowerforward end of drawbar 38 to avoid stressing the link rods 76.

The roll coupling embodiments of FIGS. 13 to 19 provide two or morevertically aligned hitches to reduce the amount of trailer weight loadedon each hitch and to resist horizontal shear forces acting on thehitches resulting from roll coupling the trailer to the tow vehicle.

FIG. 13 illustrates, as an example, a vertically aligned combination ofa pintle hook 64 and a drop-pintle coupling 80 mounted to a truck towingapron 82. Lunette rings 68 are mounted on trailer drawbar 38 by pitchplate 84. Pitch plate 84 is pivotally mounted on the end of drawbar 38providing pitch rotation in direction I around pitch pin 36. Lunetterings 68 mount into hook 64 and coupling 80. Hook 64 is opened bylifting the closing arm 64 b in direction J. Coupling 80 is opened byunlatching and dropping hook 80 a in direction K.

FIG. 14 illustrates how another vertically aligned hitch arrangement maybe used to employ two pinned couplers 86 above and below a pintlecoupler 64 attached to towing apron 82 such as would be found on a dumptruck equipped for towing a tandem axle pony trailer. Pins 86 a arejournalled downwardly through vertically aligned eyes in collars 86 band through a corresponding eye in each arm 84 a on pitch plate 84interleaved between each pair of collars 86 b. Pitch plate 84 is pinnedat 36 to allow pitch motion.

FIG. 15 illustrates a combination of a pintle hook 64 and a drop-pintlecoupling 80 connected to a trailer drawbar 38 via pitch plate 84 that ispinned by pitch pin 36 to a longitudinal roll axis pin 88. Pin 88 may belocked to prevent roll motion or released to allow for roll motion aboutaxis D to selectively provide roll coupling when desired by an operator,for example when travelling on a highway. In the example of a lock forpin 88, a roll lockout handle 90 rotates vertically in direction Laround a pin 92 passing through the lockout handle 90 and trailerdrawbar bracket 94 to disengage the locking flange 90 a of lockouthandle 90 from a slot 88 a in the end of the roll axis pin 88 foroff-road use of the tow vehicle and trailer. A safety pin 96 may beinserted through the lockout handle bracket 94 attached to the trailerdrawbar 38 and lockout handle 90 to hold the lockout handle in eitherits open or closed position.

A proximity sensor or electric switch (such as sensor 38 a) in FIG. 15should be provided to activate a warning device in the cab of the towvehicle so as to alert the operator that the roll coupling lock has notbeen engaged.

In FIG. 15 the roll lockout handle 90 is illustrated in the lockedposition. In FIG. 16 the handle 90 is illustrated disengaged from slot98 a in a roll swivel pin assembly 98 mounted on roll axis pin 88 toprovide unrestricted roll movement when operating the vehicle off roadon rough and uneven terrain.

FIG. 16 illustrates the roll coupling assembly of FIG. 15 with theaddition of a yaw dampening cylinder 100 pivotally attached to drawbar38 and connected to a second pintle coupler 64 attached to tow apron 82laterally offset from the first pintle coupler 64 and coupling 80 so asto control rearward amplified sway around the yaw axis on combinationvehicles having multiple trailers such as those known conventionally as“A” trains and triples.

There are concerns in the trucking industry regarding the loss ofsteering tire friction on tri-drive trucks when the frame is loaded aftof the driving axles. FIG. 17 illustrates a fluid cylinder such aspneumatic cylinder 102 that is pivotally anchored to the trailer drawbar38 by pin 104. The cylinder 102 is pivotally connected to the pitchplate bracket 84 by pin 106 to apply forward pressure on the uppercoupler 64 when the cylinder is sufficiently charged to transfer weightforward of the driving axle group to the steering axle of the towvehicle such as the steering axle of a ti-drive truck.

On occasion it may be necessary to move a trailer with a tow vehiclethat is not equipped for roll coupling. A pin 108 may be insertedthrough an aperture in the pitch plate bracket 84 and through trailerdrawbar 38 to prevent pitch rotation around pitch pin 36 when thetrailer is attached to a tow vehicle that is equipped with only onecoupler.

FIG. 18 illustrates a means of cushioning torsional shock andrestricting roll rotation on torsionally rigid trailers. The drawbar 38has two vertical plates 110 attached at the upper and lower quadrants ofthe round tube of the drawbar 38 to apply pressure on the four rubberblocks 112 contained inside the shock dampening roll housing 114 asbetter seen in the sectional view of FIG. 19 when rotational movementoccurs around the roll axis D in the center of the drawbar tube 38. Thefour rubber blocks 112 are provided to cushion and resist roll rotationin direction M of the drawbar assembly 38 within the confines of theroll housing 114. The housing assembly is held in place using three ormore mounting bolts 116 passing through slotted holes in the drawbar 38to prevent excessive roll rotation. It is understood that a variety ofmethods for reducing torsional shock and strain may be employed bysomeone skilled in the art and that cushioning the mounting bracket onthe tow vehicle could alternatively provide similar torsional stressrelief.

The coupling embodiments of FIGS. 20 to 26 illustrate how two or morehorizontally aligned hitches may be used to achieve the roll couplingaccording to the present invention.

FIG. 20 illustrates three pintle hook couplers 64 mounted to the end ofa truck or trailer frame 40 and in particular to cross member 42. Thecenter pintle hook connects with the centre lunette ring 68. The centrelunette ring 68 is mounted to housing 118. Beam 120 is mounted tohousing 118 by roll axis pin 122 for rotation about axis D. Pin 124 ismounted through corresponding apertures in housing 118 and beam 120 toprevent roll rotation about pin 122. Pin 124 may be removed to allowroll rotation. The beam 120 has a laterally spaced apart pair of lunetterings 68 attached to the front of each end of beam 120 to engage withthe corresponding pintle couplers 64 attached laterally spaced apart onthe tow vehicle. The three horizontally aligned pintle couplers 64 allowpitch rotation about axis N. The trailer drawbar 38 is pivotallyconnected to the housing 118 by kingpin 10 to provide yaw rotationaround king pin 10.

FIG. 21 illustrates the components of FIG. 20 as they would appear withpin 124 removed from its aperture 124 a in housing 118 and the drawbar38 rolled to the right about axis D. FIG. 22 illustrates those samecomponents with pin 124 replaced as they would appear when the towvehicle and trailer are making a very sharp right turn or the towvehicle is backing up and jack-knifing the trailer to the right so as torotate the drawbar about the kingpin.

FIG. 23 a illustrates a further alternative embodiment. A shaft 126 a(shown in FIG. 23 b) runs along axis D through beam 120. The centrelunette ring 68 is mounted to the front of shaft 126 a and yoke 126 ismounted to the rear end. Yoke 126 is thus pivotally mounted to beam 120for rotation around axis D and pivotally mounted to drawbar 38 bykingpin 10 to provide yaw rotation around kingpin 10. A pin such as 128may be journalled through aperture 126 b when aligned with acorresponding aperture in beam 120 so that pin 128 is inserted throughboth apertures when yoke 126 is vertical so as to selectively lock yoke126 to prevent roll rotation and thus provide roll coupling. As is thecase with other embodiments, the hitch assembly may be symmetrical asshown for example in FIG. 23 a or asymmetric (that is, extending only toone side of axis D) as illustrated in FIG. 23 b.

FIGS. 24 to 26 illustrate how horizontally aligned hitches may be usedto roll couple an “A” train dolly.

FIGS. 24 and 25 illustrate the roll coupling assembly of FIG. 20 mountedto the rear end of a tow vehicle (truck or trailer) frame 40 on crossmember 42. A second pair of lunette rings 130 are mounted laterallyspaced apart to the back of beam 120. Yaw rotation about kingpin 10 maybe selectively prevented by attaching a pair of criss-crossed chains 131or other elongate mechanical bracing means diagonally between lunetterings 130 and a third pair of lunette rings 132 mounted on the dollyframe 134. The chains are removed when it is desired to travel andprovide for yaw rotation about kingpin 10 as seen in FIG. 26.

Some tuck/trailer combinations use 5^(th) wheels mounted aft of thetruck frame to attach the trailer to the truck. 5^(th) wheel hitches arebulky and their design inherently provides roll coupling between twovehicle units. One disadvantage of using 5^(th) wheels in thisconfiguration is that the excessive hitch offset distance decreases yawstability and steering traction. A second disadvantage is that the truckand trailer frames are unnecessarily stressed when operating the vehicleon uneven terrain and a third disadvantage is that it is difficult toconnect and disconnect the trailer on uneven terrain.

FIG. 27 illustrates a truck hitch assembly 210 that could be attached tothe rear of a truck via a towing apron 212. The truck hitch assembly isconnected to a trailer hitch assembly via two vertical pins 214 toprovide yaw rotation and the trailer hitch assembly will in turn beattached to the front of a trailer drawbar. The trailer hitch in thisillustration is connected to the truck hitch assembly via pins 214passing through two lunette rings 216 that are attached to a pitchbracket 218 that rotates around a pitch pin 220. The pitch pin connectsthe pitch bracket to the roll bracket 222 that is pivotally attached tothe roll housing 224 via roll pin 226. The roll assembly rotates indirection P about axis of rotation Q up to 15 degrees in eitherdirection suspended on plates 230 and 231 within the confines of theroll housing. Plates 230 and 231 are mounted to collars 230 a and 231 arespectively. The pin 226 is journalled through the collars and throughsleeve 226 a extending therebetween. Sleeve 226 a is welded to top plate224 b of housing 224. The roll assembly may be selectively locked in avertical position by engaging roll lockout pin 228 with the front plate230 of the roll assembly. The roll lockout pin 228 slides horizontallythrough sleeve 232 that is welded in forward end of the lower plate 224a of the roll housing. Linkage 234 connects the roll lockout pin 228 tothe roll lockout handle 236 via a roll lockout arm 238 and axle 240.Rotating handle 236 in direction R rotates axle 240 and arm 238 indirection R′ thereby draining linkage 234 in direction R″. Pullinglinkage 234 in direction R″ compresses spring 234 a against slide 234 bthereby urging slide 234 b in direction S. Slide 234 b is connected topin 228. Pin 228 thus is extracted from plate 230 as the slide moves indirection S. The return of handle 236 urges pin 228 to re-engage plate230 under the return biasing force of spring 234 c.

FIG. 28 illustrates another view with an alternative hitch configurationusing two pintle couplers 242 in place of the hitch assembly 210.

FIG. 29 provides a better view of the roll lockout pin (228) and sleeve(232) welded in the lower plate of the roll housing.

FIG. 30 illustrates the roll lockout linkage 234 in a section view withright side of the roll housing removed. The lockout pin 228 isillustrated in the “locked” position. A proximity sensor or electricalswitch 244 may be installed to warn the truck driver when the rollcoupling is disengaged.

FIG. 31 illustrates an alternative embodiment of the invention in asection view with the right side of the roll housing removed. Thisembodiment uses compressed air bellows 246 to engage a locking device248 with the forward plate 230. Alternatively electric or hydraulicactuation may also be employed to engage a locking device. The lockingdevice 248 is illustrated in the “disengaged” position. The lockingdevice may be remotely activated either manually or automatically whenthe trailer reaches an adjustable predetermined speed. A proximitysensor 244 and adjustable trigger plate 250 cooperate to alert the truckdriver when the locking device is disengaged.

FIG. 32 illustrates a truck hitch assembly 310 with guide plates 312that may be attached to the rear of a truck via a towing apron 314. Thetrailer hitch in this embodiment is connected to the truck hitchassembly via pins 316 passing through a pitch bracket 318 that rotatesaround a pitch pin 320. The pitch pin connects the pitch bracket to theroll bracket 322 that is pivotally attached to the drawbar 324 via frontplate 328. The roll bracket rotates up to 15 degrees in either directionwithin the confines of the slots 328 a provided in the front plate 328of the drawbar. Bolts 326 in plate 330 pass through slots 328 a so as toanchor the roll bracket to the drawbar assembly. The roll bracket may beselectively locked in a vertical position by engaging roll lockout dog332 with the front plate 328 and the roll bracket 322. The roll lockoutdog 332 is mounted on a shaft 334 connected to the roll lockout handle336. The dog is centered in the drawbar with two spacers 338.

FIGS. 36-38 illustrate alternative trailer hitch components in both the“locked” and “unlocked” positions. This embodiment provides a yaw pinboss 340 bored to accept a yaw pin 316 to attach the trailer hitch tothe truck hitch assembly similar to the truck hitch illustrated in FIGS.32-35. The yaw pin boss is pivotally connected to the roll housing 342via pins 344 to permit up to 15 degrees of roll rotation in direction Tabout axis U when the locking plates 346 are extended to the unlockedposition by rotating nut 348 in direction “V”. The roll housing ispivotally connected via pins 350 to the trailer drawbar 324. Housing 342is free to rotate in direction T independently of rotation of nut 348 indirection V.

There are occasions when vehicles operating on rough terrain should notbe roll coupled. For instance, when the loaded trailer of a loggingtruck slips over a steep bank along the road the operator of the loggingtruck would prefer to allow the trailer to be free to roll completely360 degrees relative to the truck so as to dump the load of logs fromthe trailer bunks before the truck is also dragged over the edge. Oneembodiment of the present invention provides a means for selectively orautomatically engaging and disengaging roll coupling components toprovide roll articulation when operating on uneven terrain and rollcoupling when operating the vehicle on the highway.

FIG. 39 illustrates a truck frame 410 attached to a tow apron 412 aswould be used on a dump truck. If this was the case the gravel box wouldbe pinned 414 at the top of the apron assembly. Attached to the towapron 412 is a hitch designed to pull trailers equipped with lunetterings 416 and trailers with roll coupling hitches. The hitch assembly onthe truck or tow vehicles has a front plate 418 attached to the apron412. The front plate 418 is attached to a top plate 420 and threesmaller plates 422 that are in turn attached to an upper pin boss 424and a lower pin boss 426 bored out to accept a yaw pin 428. Pin bosses424 and 426 may be fitted with rollers 425 to reduce wear between thepin bosses and alignment forks 440 and 442 (shown in FIG. 40). The pinbosses are welded to their corresponding plates 420, 422. The rollersare steel collars which are free to rotate around the pin bosses. Thevertical alignment of the pin bosses may be parallel to the apron 412 toallow the trailer hitch assembly to rotate freely around the yaw axis orthe pin bosses may be tipped (for example about five degrees) slightlyforward towards the tow apron 412, so that an angle a between thecentroidal axis through the pins and the horizontal may be about 85degrees, to provide a pre-load roll force that will cause the trailer tolean into the corner. A no-slack slider 430 is provided to provideconstant pressure on the drawbar eye or lunette ring 416.

FIG. 40 illustrates the same truck configuration attached to a trailerdrawbar 432 with a mating roll coupling hitch assembly. This drawingillustrates a spring loaded pneumatic service chamber 434 that is usedto apply constant pressure on the no-slack slider 430 illustratedclearly in FIG. 39. The trailer is connected to the truck hitch via thedraw eye 436 using yaw pin 428. The draw eye is part of the Pitchassembly 438 equipped with two alignment forks 440 and 442 that engagewith the upper and lower pin bosses 424 and 426 respectively. Thealignment forks 440 and 442 serve three purposes. They guide the trailerhitch into position when connecting the tow vehicle to the trailer, theyhold the hitch in position to enable the yaw pin 428 to be easilyinserted or withdrawn and they communicate trailer roll motion to thetow vehicle. The pitch assembly 438 is pivotally connected with the rollassembly 444 via the pitch pin 446. The roll assembly 444 permits thetrailer to oscillate on the roll axis unless the roll lockout pin 448 isengaged with the roll assembly front plate 450 and the roll housing 452and roll housing front plate 454. The roll housing is equipped with anassess port 456 to accommodate service hoses and wires 458 that passthrough the drawbar 432 to the trailer body (not shown).

FIG. 41 provides a better view of how the roll assembly 444 is pivotallyconnected with the roll housing 452 that is attached to the trailerdrawbar 432.

FIG. 42 is a cut-a-way view of the trailer hitch as the concept could beapplied to trailers designed to be pulled behind gravel trucks. Thisdrawing better illustrates how the pitch assembly 438 is pivotallyconnected with the roll assembly 444 via pitch pin 446. The rollassembly 444 in turn is pivotally connected with the roll housing 452via roll pin 460. This drawing also illustrates a spring loaded servicechamber 434 that by default forces the roll lockout pin 448 housed in apin boss 464 in the roll housing 452 forward through a hole journalledthrough the front plate of the roll assembly 450 and finally through ahole journalled through the roll housing front plate 454 to selectivelyprevent the roll assembly 444 from rotating around roll pin 460. Springloaded service chamber 434 contains a spring 434 a (shown by way ofexample diagrammatically in dotted outline) which urges pin 448 indirection W against the return biasing force of pneumatic bellows 434 bwhich, when inflated, collapse spring 434 a thereby extracting pin 448in a direction reverse to direction W, unlocking the roll coupling.Pneumatic inlet 434 c is on the forward side of service chamber 434 toillustrate that pin 448 locks out roll rotation, i.e. locks the rollcoupling, under spring pressure from spring 434 a. When pin 448 is underthe spring pressure, the roll coupling will lock as soon as the holes inthe front plate of the roll assembly and in the roll housing front platealign with the pin boss.

The spring loaded service chamber 434 may be manually activated by theoperator at any speed to roll couple the vehicle but if the driverforgets to lock out roll rotation manually, the lockout pin 448 willengage automatically under spring pressure the release of which so as toengage the roll coupling is controlled by the antilock braking systemmodule of the trailer (for example as the antilock system activates atits preset speed) or alternative means when the vehicle reaches a presetroad speed (for example 30 kilometers per hour). The operator mayselectively disengage the roll lockout pin 448 pneumatically but onlywhen the vehicle is travelling below the safety threshold speed.

FIG. 43 illustrates the same concept in an alternative embodiment as itcould be applied to trailers with straight drawbars such as dollies,pony trailers and full trailers including those that are attached tologging trucks. Trucks that have long frame rails 410 extending adistance past the driving axles may need to be stiffened using a torsionbox assembly 466. The torsion box 466 and the truck hitch 468 aspreviously described can be attached to a lunette ring 416 via yaw pin428 or a trailer hitch designed to provide roll coupling.

FIG. 44 illustrates the forward section of a drawbar 432 connected to aselective roll coupling hitch assembly 470 that when disengaged may roll360 degrees around the roll axis. Pitch assembly 438 is similar to thepitch assembly illustrated in FIGS. 40-42.

FIG. 45 illustrates the trailer hitch assembly. The trailer hitch haspneumatic spring loaded service chamber 434 to lock the roll assembly444 to the roll housing 452.

FIG. 46 is a cut-a-way of the hitch assembly that illustrates how thespring loaded service chamber 434 is connected to a knife assembly 472that slides in a slotted guide 474 in the roll housing 452. When theknife 472 is forced forward while the roll assembly 444 is in alignmentwith the roll housing 452 the forward portion of the knife 472 engageswith a mating slot 476 in the round roll assembly tube 478. When theknife is engaged with the upper and lower slots in the roll housing 452and the upper and lower slots in the roll assembly 444 the trailer hitchwill be roll coupled with the tow vehicle. When the knife 472 isdisengaged from the slots in the roll assembly 444 and resting in theslots 474 provided in the roll housing 452, the round tube 478 which ispart of the roll assembly 444 can rotate freely around the inner roundtube 480 that is welded to and part of the roll housing 452. The innerround tube is capped with a front plate 482 that anchors a threaded bolt484 that protrudes through a plate 486 in the forward end of the roundtube 478 of the roll assembly 444. A threaded nut 488 prevents the rollassembly from sliding forward off the inner round tube.

As with the previous embodiment of the invention illustrated in FIGS. 39through 42, FIGS. 43-46 are illustrative examples of how the presentinvention may be implemented. Someone skilled in the art could findalternative methods, and these are intended to fall within the ambit ofthe present invention, to assemble a rotatable roll assembly with atrailer drawbar, selectively lock and unlock the roll coupling assemblyat a pre-set speed, and to align the roll coupling hitch assemblieswhile connecting or disconnecting the trailer and the tow vehicle.

In the embodiment of FIG. 47-49, upper and lower guide plates 30 aremounted on towing apron 43. A pintle coupler 242 is mounted to towingapron 43 between the upper and lower guide plates 30. The correspondinglunette ring 216 is mounted to pitch bracket 218′. The pitch bracket ismounted to the drawbar of the trailer for example by the use of aselective roll coupling hitch assembly 470 described above, or otherroll coupling assemblies providing for selective locking of the rollcoupler. King pins 10 are mounted on the forward arms 218 a′ of thepitch bracket 218′ and engage in guide plates 30.

Transfer trailers are used in the aggregate industry to maximize payloadand/or to deliver material into construction sites where it is difficultto unload pony and full trailers. The unique feature about transfertrailers is that the gravel boxes on transfer trailers are designed tofit inside the gravel boxes on the trucks for dumping. After thetransfer trailer gravel box has been emptied, the gravel truck straddlesand backs over the trailer drawbar to position the truck directly infront of the trailer frame to align and slide the trailer gravel boxback on to the trailer frame. This creates two problems that contributeto vehicle instability. Firstly, in order to be able to transfer the boxfrom the trailer into the truck box, the transfer box must ride highenough on the trailer to be vertically aligned with top of the rails inthe truck box. Raising the box increases the height of the center ofgravity. Secondly, the trailer box must also be narrow enough to fitinside the truck box so in order to carry a full load, the height of theload inside the trailer box must be increased. These design limitationscontribute to dynamic instability problems with these trailers becausethe center of gravity is comparatively much higher than with othertrailers designed for hauling aggregate.

The present invention provides a means for roll coupling the transfertrailer with the truck to improve dynamic stability. When anchored tothe truck, the roll coupling hitch prevents the trailer drawbar fromrotating around the roll axis to improve stability on the roll axis. Thesecond distinguishing feature of the roll coupled transfer trailer isthat the drawbar slides under the trailer to enable the truck to back upto the front of the trailer to get into position for transferring thetrailer box in and out of the truck box. This enables the drawbar to bemanufactured from torsionally rigid material that is too bulky for thetruck to back over to reach the trailer frame. In order to attach anddetach the trailer hitch from the truck, the drawbar may be selectivelyraised or lowered using the trailer hydraulic system to align the hitchcomponents. This invention improves productivity by enabling the trailerto be coupled or uncoupled more quickly and improves safety by makingthe combination vehicle more stable.

As seen in FIGS. 50 and 51, the dolly assembly for a transfer trailer500 includes a telescopic drawbar 510 telescopically mounted throughtrailer coupler 512. A roll coupling hitch assembly 514 is attached tothe forward end of the drawbar. Pneumatic actuators may be provided tolock and unlock the drawbar to telescope the drawbar from the trailercoupler, and hydraulic actuators 632 may provide for selectively liftingthe end of the drawbar 510 to align with the hitch.

FIG. 52 illustrates a top view of a roll coupled four axle (quad)transfer trailer 610 and FIG. 53 illustrates a side view of the transfertrailer 610 attached to the rear of a gravel truck 612. The two vehiclesare connected together with a roll coupling hitch 614 via the trailerdrawbar 616. The trailer drawbar connects with a dolly 618 that ispivotally connected via a turntable 620 to the trailer frame 622. Thetrailer is designed to transport a trailer gravel box 624 to a job siteand then slide the trailer gravel box 624 off the trailer frame 622 andinto the truck gravel box 626.

The drawbar 616 selectively slides in direction X through a drawbarhousing 628 that is pivotally connected to the dolly 618 and the dollyframe 630 that attaches to the turntable 620. The dolly frame 630 housesone or more hydraulic cylinders 632 that are pivotally connected to thedolly frame 630 for the purpose of rotating in direction Y the drawbarhousing 628 around the horizontal axis running through to center of pin634 that also pivotally connects the walking beams 636 to the dollyframe 630.

FIG. 54 illustrates a top view of the dolly assembly with the drawbarillustrated in the retracted position. FIG. 55 illustrates a sectionview to better illustrate how the housings are assembled.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

1. A roll coupling system for roll coupling the drawbar of a trailer tothe rear of a tow vehicle, the system comprising: a roll torque transferstructure including at least one first load bearing surface on a firstload bearing structure mountable to the rear of the tow vehicle andadapted to be mounted closely adjacent thereto, and at least one secondload bearing surface on a second load bearing structure mountable to thefront of the trailer drawbar, wherein said first and second load bearingsurfaces cooperate so as to releasably mate with one another for towingof the trailer behind the tow vehicle and, when the trailer is so matedto the tow vehicle, are distributed across a substantially planarinterface between the rear of the tow vehicle and the front of thetrailer drawbar so as to distribute torque imparted to the drawbar byrelative rolling motion between the trailer and tow vehicle to the rearof the tow vehicle by distribution of resulting moments which aretransferred to the tow vehicle so that the cumulative combined rollresistance of the tow vehicle and trailer resist the rolling of thetrailer about the drawbar, a coupling alignment mechanism to adjust therelative orientation of said first and second load bearing surfaces insaid substantially planar interface so as to align said first and secondload bearing surfaces for said mating with one another, wherein saidcoupling alignment mechanism includes a selectively rotatable coupler,selectively rotatable about the roll axis of the trailer drawbar,mounted between the front of the drawbar and the rear of the towvehicle, and wherein said selectively rotatable coupler includes aselectively releasable lock, and wherein said coupling alignmentmechanism includes at least one roller mounted between said first andsecond load bearing surfaces to reduce wear between said first andsecond load bearing surfaces.
 2. The system of claim 1 wherein saidfirst and second load bearing surfaces include at least one V-shapedguise mating, in the V-shape of said guise, with a corresponding pin,and wherein said at least one roller is mounted on said pin.
 3. Thesystem of claim 1 wherein said lock locks said coupler in a fixed rollcoupling position, fixed relative to rotation about said roll axis, upona pre-set forward translation speed being attained by the tow vehicleand trailer.
 4. The system of claim 1 wherein said first and second loadbearing surfaces mate at least two spaced apart load transfer points onsaid substantially planar interface, and wherein said planar interfaceis inclined from the vertical so that an upper position of said planarinterface is tipped towards the tow vehicle so as to provide a pro-loadroll force acting on the trailer to cause the trailer to lean into acorner, wherein an upper load transfer point is positioned forward of alower load transfer point of said spaced apart load transfer points. 5.The system of claim 4 wherein said male load bearing structure includesa hook and wherein said female load bearing structure includes a collarhaving an aperture sized for snug mating with said hook so as to journalsaid hook in said aperture, and wherein said first and second loadbearing structures are mounted at each of said at least two spaced apartload transfer points, and wherein said at least two spaced apart loadtransfer points form a substantially linear array.
 6. The system ofclaim 1 wherein said lock includes a male portion interlocking into acorresponding female portion, and wherein said male portion is urgedinto said interlocking with said female portion by a default driverbiasing said male portion into registry with said female portion so thatsaid roll coupling defaults to said locking of said coupler to rollcouple the tow vehicle and trailer together.
 7. The system of claim 6wherein said default driver includes a resilient driver.
 8. The systemof claim 7 wherein said resilient driver includes a spring.
 9. Thesystem of claim 6 wherein said lock further includes a return biasingdriver for selectively unlocking said roll coupler so as to dis-engagesaid roll coupling of the tow vehicle and trailer.
 10. The system ofclaim 7 wherein said lock further includes a return biasing resilientdriver for resiliently biasing said lock to selectively unlock said rollcoupling.
 11. The system of claim 6 wherein said roll coupling includesa pair of plates, a first plate of which is adapted to be mounted to therearmost end of the tow vehicle, a second plate of which is adapted tobe mounted to the front end of the drawbar of the trailer, and whereinsaid pair of plates are substantially flush against one another when thetrailer is coupled to the tow vehicle, and wherein said pair of platespivot relative to one another in flush rotation one over the other, andwherein each plate of said pair of plates has an aperture, and whereinwhen said apertures in said plates are aligned, the trailer is alignedfor roll coupling with the tow vehicle, and wherein said male portion ismounted in one of said apertures and the other of said apertures is saidfemale portion.
 12. The system of claim 11 wherein said male portion isan elongate member which is projected into snug mating with said femaleportion to effect said roll coupling.
 13. The system of claim 12 whereinsaid default driver is a linear driver biasing said member linearly intoregistry in said aperture of said female portion.
 14. The system ofclaim 13 further comprising a return driver selectively actuable toextract said member from said female portion so as to dis-engage saidroll coupling.
 15. The system of claim 14 wherein said return driver isa linear driver extracting said member co-axially with said defaultdriver.
 16. The system of claim 15 wherein said default driver and saidreturn driver are resilient.
 17. The system of claim 16 wherein saidlinear driver and said return driver are each chosen from the groupcomprising a resilient spring driver, a pneumatic driver.
 18. The systemof claim 14 wherein said second plate is adapted to be mounted on thedrawbar of the trailer and wherein said first plate is adapted to bemounted to the rear of the tow vehicle.
 19. The system of claim 18wherein said roll torque transfer structure first and second loadbearing surfaces are mounted to said first plate, opposite said secondplate.
 20. The system of claim 1 wherein said lock is adapted to bebiased into said locking upon receipt of a locking trigger correspondingto said pre-set forward translation speed.
 21. The system of claim 20further comprising a locking driver locking said lock and a returndriver unlocking said lock, and wherein said locking driver iscontinually biasing said lock into said fixed roll coupling position,and wherein said return driver return biases said locking driver so asto prevent said locking until said trigger is received whereupon saidreturn driver dis-engages from said return biasing of said lockingdriver.
 22. The system of claim 21 wherein said locking driver and saidreturn driver are both resilient drivers.